This article discusses how to attempt to repair failed VSS writers on a protected machine that is running Windows 8, Windows Server 2012, or higher.
Datto appliances use the Volume Shadow Copy Service, also known as VSS Writers, to run backups. For more information about VSS Writers, check out VSS Explained: Common Writers, Services, and Hotfixes Available
When VSS writers on Windows 8 or Windows Server 2012 fail it could cause backups to fail. To repair VSS writers, the process usually involves using the VShadow utility, but this tool is not available for the above two operating systems. This article describes an alternative method.
VSS Writers, Services and Processes
Below is a chart including the various VSS writers along with the associated process and service.
|VSS Writer||Process (.exe)||Service|
|ASR Writer||VSS||Volume Shadow Copy|
|BITS Writer||BITS||Background Intelligent Transfer Service|
|COM+ REGDB Writer||VSS||Volume Shadow Copy|
|DFS Replication Service Writer||DFSR||DFS Replication|
|DHCP Jet Writer||DHCPServer||DHCP Server|
|FRS Writer||NtFrs||File Replication|
|FRSM Writer||srmsvc||File Server Resource Manager|
|IIS Config Writer||AppHostSvc||Application Host Helper Service|
|IIS Metabase Writer||IISADMIN||IIS Admin Service|
|Microsoft Exchange Replica Writer||MSExchangeRepl||Microsoft Exchange Replication Service|
|Microsoft Exchange Writer||MSExchangeIS||Microsoft Exchange Information Store|
|Microsoft Hyper-V VSS Writer||vmms||Hyper-V Virtual Machine Management|
|MSMQ Writer||MSMQ||Message Queuing|
|MSSearch Service Writer||WSearch||Windows Search|
|NTDS||NTDS||Active Directory Domain Services|
|O_Search VSS Writer||OSearch||Office SharePoint Server Search|
|O_Search 14 VSS Writer||OSearch14||SharePoint Server Search 14|
|Registry Writer||VSS||Volume Shadow Copy|
|Shadow Copy Optimization Writer||VSS||Volume Shadow Copy|
|SPSearch VSS Writer||SPSearch||Windows SharePoint Services Search|
|SPSearch4 VSS Writer||SPSearch4||SharePoint Foundation Search V4|
|SqlServerWriter||SQLWriter||SQL Server VSS Writer|
|System Writer||CryptSvc||Cryptographic Services|
|TermServLicensing||TermServLicensing||Remote Desktop Licensing|
|WIDWriter||WIDWriter||Windows Internal Database VSS Writer|
|WINS Jet Writer||WINS||Windows Internet Name Service (WINS)|
|WMI Writer||Winmgmt||Windows Management Instrumentation|
Repairing VSS Writers
There are a few steps that can be taken to attempt to repair the VSS writers on a machine:
- On the target machine, open an elevated command prompt with administrator privileges.
- Run the command
vssadmin list writers
- Once that command returns, take note of any writers in a Failed state.
- Open services.msc on the machine. Reference the above table, and stop the services for the VSS writers which have failed.
- Open task manager and hard kill the processes for the related failed VSS writers.
- Return to services.msc and restart the related services.
vssadmin list writersagain to make sure the VSS writers are now showing as stable.
It is imperative that all VSS writers be in a stable state on the protected machine. If there are any writers that are failed, they can cause backups to fail.